Fan guards are mounted on fans to protect from injury that would result from contact with the rapidly rotating blades. Such fan guards often consist of a pair of guard portions each constructed out of wire and/or screen bent into various forms and having means for securing the portions together. Typical examples of these types of fan guards are shown in U.S. Pat. Nos. 1,114,459 and 3,787,142.
The aforedescribed types of fan guards are relatively inexpensive in construction and employ securing means to provide access to the blades. However, a fan guard that incorporates a simple construction that provides strong resistance to axial separation of the guard portions and is easily assembled has not yet been available for use.
It is an object of the invention to provide a fan guard having a simplified construction comprising front and rear guard portions wherein each of the guard portions include a plurality of homogeneously extending P-shaped tabs that interlock to form abutments with each other to provide strong resistance to axial separation.
It is another object of the invention to provide a fan guard having a simplified construction that can be readily assembled and disassembled and is of low manufacturing cost.
It is yet another object of the invention to provide a fan guard comprising a simplified construction, including front and rear guard portions, that allows air to flow through without being unduly obstructed yet, is of high strength, and when the guard portions are secured in assembled relationship is free of rattling or other noises from vibration imposed on the guard portions from the associated fan motor.
In the practice of the invention the fan guard has front and rear guard portions each including a plurality of wire rings concentrically mounted on a plurality of radially extending support wires. The rear portion is mounted to the frame of the fan motor. Some of the radially extending wires are formed with a loop at the outer end, whereon homogeneous P-shaped tabs extend radially outwardly. When the guard portions are assembled together the rings defining the portions' periphery are adjacent, though slightly spaced, the tabs are bolted together and a cage is formed enclosing the fan blades.
The tabs are formed by bending the outer end of certain of the radially extending support wires into a loop defining a slot having parallel edges. The tabs include front and back sides and are offset with respect to the joining plane such that when the guard portions are assembled the slots align and the front side of the tabs of the front portion interlock with the back side of the tabs of the rear portion to provide strong resistance to axial separation of the guard portions. A carriage bolt is passed through the aligned slots to mate with a nut to secure the guard portions together and as the square neck of the carriage bolt is closely received between the parallel portions of a tab loop a rotation of the bolt during tightening is prevented.
To assemble the guard portions it is merely necessary to bring them together with the peripheral edges of the portions in adjacent relationship so that the plane of the front portion tabs are "behind" the plane of the tabs of the rear portion. By rotating the front portion the offset tabs interlock front-to-back as the tab slots align to receive a carriage bolt and the bolt nut is tightened to secure the guard portions together. To disassemble the fan guard simply loosen the nuts and remove the carriage bolts from the slots. Rotating the front guard portion misaligns the interlocked tabs to allow separation of the guard portions.